The benefits of antiretroviral therapy (ART) to HIV-infected patients are significant. However, ART interruption is coupled with a rapid rebound in plasma viremia. This rebound signifies the ultimate challenge surrounding ART - its inability to completely eradicate HIV. Understanding the mechanisms by which the virus is able to persist in the face of ART is necessary in order to identify strategies that may interrupt viral persistence and ultimately lead to virus eradication. There is a definite need for the implementation of in vivo models where these mechanisms can be elucidated and induction/eradication interventions aimed at virus eradication can be evaluated. Novel humanized mice (bone marrow-liver-thymus or BLT mice) developed in our laboratory could serve effectively in this capacity. Humanized BLT mice exhibit systemic reconstitution (including in the gut and vaginal mucosa) with a complete and functional human immune system. The functionality and usefulness of BLT mice in the study of HIV persistence and eradication will become evident when the following aims are completed, wherein the parameters of viral persistence will be established and novel eradication approaches will be tested. The long-term goal of our project is to develop and implement an in vivo animal model in which novel protocols for HIV-1 eradication can be evaluated. This project will first compare different drug regimens aimed at establishing durable suppression of viremia in humanized BLT mice to allow the detailed study of persistence and latency. We will then establish the sites of residual virus infection that persist despite ART. After the establishment ofthis model, this project will evaluate the effect of novel reagents to disrupt latency with the ultimate long-term goal of establishing virus eradication. Our goals will be achieved by pursuing the following specific aims: Specific Aim 1: To establish an optimal drug regimen forthe durable suppression of viremia in humanized BLT mice.Specific Aim 2: To characterize the nature and the anatomical location of viral reservoirs which persist in BLT mice undergoing ART.Specific Aim 3: To characterize the effect of select inducfion therapeufic interventions for their ability to eradicate virus from infected BLT mice, by significantly delaying or preventing rebound after disconfinuafion of antiretroviral therapy. HIV eradicafion is a daunting task that has proven to be extremely difficult to achieve in patients. The significance of this project rests on its goal: to develop and implement a novel in vivo model in which eradication approaches aimed at the development of a potential "cure" for HIV infection can be evaluated in vivo prior to clinical implementation.